December in Context
A round-up of some of this month’s most exciting biology news.
Coronavirus: Vaccine Approval and the New UK Variant
Unsurprisingly, we round out the year with both science and mainstream media dominated by coronavirus news. Shortly after the preliminary results of several phase III clinical trials had been announced, the UK became the first country to approve a COVID-19 vaccine on 2nd December. Front-line care workers, care home staff and residents soon received their first doses of the Pfizer and BioNTech vaccine with more than 600,000 people receiving their first doses between the 6th and 20th of December.
In the following weeks, the US Food and Drug Administration (FDA) has granted emergency use authorisation of both the Pfizer and Moderna vaccines, and the results from the AstraZeneca-Oxford vaccine clinical trials were the first to be formally published.
Although the speed of vaccine development, authorisation and use is a remarkable achievement, there are still many lingering questions and concerns which will affect how governments respond to the pandemic as we head into 2021. In particular, researchers are asking how long will vaccine-induced immunity last, will the virus evolve to evade vaccine-induced immunity, and how well do the vaccines prevent disease transmission in the general population? It will take months of follow-up to determine the answers.
Despite these questions, as cases of coronavirus begin to rise again the UK, with 53,135 new cases recorded on the 29th, and much of the country facing harsher Tier4 lockdown rules, it comes as good news that the Oxford-AstraZeneca vaccine has also been approved and 100 million doses ordered.
On 14th December, Health Secretary Matt Hancock announced the discovery of a new variant of COVID-19 in the UK, known as B.1.1.7, which is thought to spread faster than the original virus. The variant has since been identified in many European countries and across the globe, including Singapore, Australia, and Japan.
It is common for new variants of viruses to appear as they replicate in cells and errors are made in copies of their genetic blueprint. B.1.1.7 is thought to have 17 changes, including the N501Y mutation in the spike protein that allows the virus to penetrate host cells. This mutation is thought to increase binding capacity of the virus and has also been reported in a different variant in South Africa.
Despite these changes, there is no evidence to suggest that the variant causes more severe symptoms of the disease or that current vaccines will be less effective against it.
Thousands of species threatened by human agricultural expansion over the next 30 years
A report from Nature Sustainability this month predicts that over 17,000 vertebrate species will lose a significant portion of their habitat by 2050, as humans clear land for food.
The authors developed a new model that estimates where agricultural expansion is most likely to occur based on historical use of the land and linked this model with projections of how much agricultural land each country will need. This highlighted exactly which species and landscapes are likely to be threatened by the predicted 3.35 million km2 agricultural expansion. Agricultural growth and thereby habitat losses were predicted to be greatest in sub-Saharan Africa and in parts of Central and South America.
The study also estimates that 1,280 species would lose at least 25% of their habitat and 96 species would lose at least 75%. As many of these species are not considered to be threatened with extinction, there are currently no conservation efforts to protect them.
Co-lead author on the paper, Dr Michael Clark from University of Oxford, insists there is still hope, “The good news is that if we make ambitious changes to the food system, then we can prevent almost all these habitat losses.”
The study examined the possibility of proactive efforts and policies to reduce demand for agricultural land and protect biodiversity. Changes such as improving crop yields in Sub-Saharan Africa, shifting to healthier and more plant-based diets in North America, and reducing food waste globally could hugely reduce agricultural land use.
Vision restored in old mice by turning back the epigenetic clock
Vision loss is a common feature of ageing, with approximately one in three people over the age of 65 having some form of vision-reducing disease. One of the most common causes of vision loss in the elderly is a glaucoma, a group of conditions characterised by damage to the optical nerve. An international team of researchers, led by scientists from Harvard Medical School, have restored vision in mice with induced glaucoma by reverting neurons in the eye to a ‘younger’ state where they are able to repair the damaged tissue.
As we age, our body changes in many ways, including changes to the chemical groups on DNA known as “epigenetic” changes, which accumulate over time. Epigenetic changes do not change your DNA sequence but can effect how your DNA is read, causing genes to be turned on and off. Co-author Prof David Sinclair, a geneticist at Harvard Medical School said “We set out with a question: if epigenetic changes are a driver of ageing, can you reset the epigenome?”
The team approached this by adopting the process used to make induced pluripotent stem cells (iPSCs). iPSCs are stem cells with the capacity to give rise to many cell types, i.e. pluripotent, which have been generated from adult cells. This is achieved by introducing four genes into the adult cells which go on to control the expression of genes needed to maintain a pluripotent state. This process is known as reprogramming.
In the new study, researchers chose three of the four genes to create iPSCs, dropping one that is associated with cancer, and delivered them to retinal neurons via viruses. A switch was included which allowed the genes to be turned on for a few days by giving the mice water with a specific drug. Following treatment, visual acuity was restored in mice with glaucoma as neurons began to regenerate. This was associated with epigenetic changes to DNA in the retinal neurons being reset to those seen in younger mice and human cells.
Although the new approach is incredibly promising, it has only been carried out in mice and will need to be refined before it can be used safely in humans. It also remains to be seen if this approach can be used in other tissues with age related degeneration.
· Clinical trials have begun for two promising gene therapies targeting the cause of sick-cell anaemia, a debilitating disease in which red blood cells are misshapen so cannot carry enough oxygen. Both treatments aim to increase production of foetal haemoglobin to replace the normal haemoglobin which is mutated in the disease, and is the cause of misshapen red blood cells.
· Scientists in the United States and Australia have discovered that some marsupials and mammals, including wombats, platypuses and squirrels, glow under UV light. This phenomenon, in which light is absorbed and re-emitted by living organisms, is known as biofluorescence. Researchers suggest that, in the case of the glowing pink squirrels and other recently discovered animals, biofluorescence may be an ancient form of camouflage.
· A study in the Journal of Arid Environments estimates that plastic waste kills around 1% of dromedary camels in the United Arab Emirates. Veterinary microbiologists at the Central Veterinary Research Laboratory in Dubai examined 30,000 dead camels, finding that 300 had guts packed with plastic, some weighing up to 64kg.